Command queuing

ABSTRACT

The present disclosure includes apparatuses and methods for command queuing. A number of embodiments include receiving a queued command request at a memory system from a host, sending a command response from the memory system to the host that indicates the memory system is ready to receive a command in a command queue of the memory system, and receiving, in response to sending the command response, a command descriptor block for the command at the memory system from the host.

PRIORITY INFORMATION

This application is a Continuation of U.S. application Ser. No.15/246,735, filed Aug. 25, 2016, which issues as U.S. Pat. No.10,146,477 on Dec. 4, 2018, which is a Continuation of U.S. applicationSer. No. 14,181,089, filed Feb. 14, 2014, now U.S. Pat. No. 9,454,310 onSep. 27, 2016, the contents of which are included herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor memory andmethods, and more particularly, to command queuing.

BACKGROUND

Memory devices are typically provided as internal, semiconductor,integrated circuits and/or external removable devices in computers orother electronic devices. There are many different types of memoryincluding volatile and non-volatile memory. Volatile memory can requirepower to maintain its data and can include random-access memory (RAM),dynamic random access memory (DRAM), and synchronous dynamic randomaccess memory (SDRAM), among others. Non-volatile memory can retainstored data when not powered and can include NAND flash memory, NORflash memory, phase change random access memory (PCRAM), resistiverandom access memory (RRAM), spin torque transfer random access memory(STTRAM) and magnetic random access memory (MRAM), among others.

Memory devices can be combined together to form memory systems, such asmemory cards, as embedded storage solutions, or as a solid state drive,for example that include memory devices. Memory systems, such as amemory card, can include non-volatile memory, e.g., NAND flash memoryand/or NOR flash memory, and/or can include volatile memory, e.g., DRAMand/or SRAM, among various other types of non-volatile and volatilememory. Flash memory devices can include memory cells storing data in acharge storage structure such as a floating gate, for instance, and maybe utilized as non-volatile memory for a wide range of electronicapplications. Flash memory devices typically use a one-transistor memorycell that allows for high memory densities, high reliability, and lowpower consumption.

Memory systems can be used as portable memory or embedded storagesolutions that are used with a number of hosts in computing systemsand/or to replace hard disk drives as the main storage device for acomputing system, as the solid state drive can have advantages over harddrives in terms of performance, size, weight, ruggedness, operatingtemperature range, and power consumption. For example, memory systemscan have superior performance when compared to magnetic disk drives dueto their lack of moving parts, which may avoid seek time, latency, andother electro-mechanical delays associated with magnetic disk drives.Memory system manufacturers can use non-volatile memory to create memorysystems that may not use an internal battery supply, thus allowing thedrive to be more versatile and compact.

A memory system can include a number of memory devices, e.g., a numberof memory chips. As one of ordinary skill in the art will appreciate, amemory chip can include a number of dies and/or logical units (LUNs),e.g., where a LUN can be one or more die. Each die can include a numberof memory arrays and peripheral circuitry thereon. The memory arrays caninclude a number of memory cells organized into a number of physicalpages, and the physical pages can be organized into a number of blocks.An array of flash memory cells can be programmed a page at a time anderased a block at a time. Operations, such as read, write, and eraseoperations, performed on a memory system can be limited by the amountresources available in the memory system to manage operations by thememory devices in the memory system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an apparatus in the form of a computingsystem including a memory system in accordance with a number ofembodiments of the present disclosure.

FIG. 2 illustrates examples of a method for command queuing in a memorysystem in accordance with a number of embodiments of the presentdisclosure.

FIG. 3 illustrates an example of a command block descriptor inaccordance with a number of embodiments of the present disclosure.

FIGS. 4A-D illustrate examples of a method for executing commands in acommand queue in a memory system in accordance with a number ofembodiments of the present disclosure.

FIG. 5 illustrates an example of a data transfer request header includedin a data transfer request in accordance with a number of embodiments ofthe present disclosure.

FIG. 6 illustrates an example of a method for command queuing andexecution in a memory system in accordance with a number of embodimentsof the present disclosure.

DETAILED DESCRIPTION

The present disclosure includes apparatuses and methods for commandqueuing. A number of embodiments include receiving a queued commandrequest at a memory system from a host, sending a command response fromthe memory system to the host that indicates the memory system is readyto receive a command in a command queue of the memory system, andreceiving, in response to sending the command response, a commanddescriptor block for the command at the memory system from the host.

A number of embodiments of the present disclosure can incorporatecommand queuing and concurrent command execution for commands that arecontrolled using embedded MultiMediaCard (e.MMC) protocol. A new commandclass can be introduced and added to the commands in the e.MMC protocolto allow for command queuing and concurrent command execution whileusing e.MMC protocol. A queued command request command, e.g., CMD 43, aready to transfer command, e.g., CMD 44, a task management functionrequest command, e.g., CMD 45, a receive data command, e.g., CMD 46, anda send data command, e.g., CMD 47, can be added as a command class tothe e.MMC protocol. These commands can be incorporated into the e.MMCprotocol to allow for command queuing and concurrent command executionwith minor changes to the e.MMC state machine of the memory system orwith just adding one state change to the e.MMC state machine of thememory system.

As used herein, “a number of” something can refer to one or more suchthings. For example, a number of memory cells can refer to one or morememory cells. Additionally, the designators “M” and “N”, as used herein,particularly with respect to reference numerals in the drawings,indicates that a number of the particular feature so designated can beincluded with a number of embodiments of the present disclosure.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 104 may referenceelement “04” in FIG. 1, and a similar element may be referenced as 204in FIG. 2.

FIG. 1 is a block diagram of an apparatus in the form of a computingsystem 100 including a memory system 104 in accordance with a number ofembodiments of the present disclosure. As used herein, a memory system104, a controller 125, or a memory device 130-1, . . . , 130-N mightalso be separately considered an “apparatus”. The memory system 104 canbe any of a number of memory systems, such as a memory card, and caninclude a host interface 106, a controller 125, and a plurality memorydevices 130-1, . . . , 130-N, e.g., solid state memory devices such asNAND flash devices, which provide storage volumes for the memory system104. The memory system 104 can be communicatively coupled to a host 102via a host interface 106, such as a backplane or bus.

Examples of hosts 102 can include laptop computers, personal computers,digital cameras, digital recording and playback devices, mobiletelephones, PDAs, memory card readers, and interface hubs, among otherhost systems. The memory system 104 can be part of a cloud storagenetworking infrastructure, for example, that is coupled to host 102 viahost interface 106, which can include a serial advanced technologyattachment (SATA), peripheral component interconnect express (PCIe), auniversal serial bus (USB), a fiber channel, or an Ethernet connection,among other connectors and interfaces. In general, however, hostinterface 106 can provide an interface for passing control, address,data, and other signals between the memory system 104 and the host 102on a command line and/or data bus, for example.

Host 102 can include a number of processors, e.g., parallel processors,co-processors, etc., communicatively coupled to a memory and buscontrol. The number of processors can be a number of microprocessors, orsome other type of controlling circuitry, such as a number ofapplication-specific integrated circuits (ASICs), for example. Othercomponents of the computing system 100 may also have processors. Thememory and bus control can have memory and other components directlycommunicatively coupled thereto, for example, dynamic random accessmemory (DRAM), graphic user interface, and/or other user interface,e.g., display monitor, keyboard, mouse, etc.

The controller 125 can communicate with the memory, e.g., memory devices130-1 to 130-N, to control data read, write, and erase operations, amongother operations. The controller 125 can include, for example, a numberof components in the form of hardware and/or firmware, e.g., one or moreintegrated circuits/logic, and/or software for controlling access to thememory and/or for facilitating data transfer between the host 102 andmemory.

In the example illustrated in FIG. 1, the controller 125 includes acommand queue 126 and a status register 127. However, the controller 125can include various other components not illustrated so as not toobscure embodiments of the present disclosure. Also, although thecommand queue 126 and the status register 127 are illustrated asresident on the controller 125, in some embodiments, the command queue126 and the status register 127 may reside elsewhere in the system 100,e.g., as an independent component or resident on a different componentof the system.

The command queue 126 can include a number of commands that have beenreceived by the memory system 104 from the host 102 for execution. Thecommand queue 126 can include the information associated with thecommand that is contained in a command descriptor block for each of thecommands in the command queue 126. The status register 127 can be aregister that stores status information, such as task dormant, taskenabled, task completed, task error, and/or task aborted, for example,for each of the commands in the command queue 126. The command queue 126and the status register 127 can include volatile memory cells, such asDRAM memory cells, for example, and/or non-volatile memory, such asFlash, RRAM, MRAM, STTRAM, and/or PCRAM memory cells, for example tostore the information associated with the commands. The data receivedfrom the host during execution of the commands in the command queue 126can have an error correction code (ECC) operation performed on the databy an ECC module prior to being stored in the memory devices 130-1 to130-N.

The memory system 104 includes a bus 120 to send/receive various signalsand/or commands, e.g., data signals, control signals, and/or addresssignals, etc., between the memory devices 130-1, . . . , 130-N and thecontroller 125. Although the example illustrated in FIG. 1 includes asingle bus 120, the memory system 104 can include a number of buses,e.g. channels, such as a number of separate data buses, control buses,and/or address buses, in some embodiments. The bus 120 is shared by theplurality of memory devices 130-1, . . . , 130-N and can have varioustypes of bus structures including, but not limited to, bus structuresrelated to Open NAND Flash Interface (ONFI). Also the bus 120 caninclude various types of bus structures, including, but not limited toCompact Flash Interface, Multimedia Card (MMC), Secure Digital (SD),consumer electronics advanced technology attachment (CE-ATA), IndustrialStandard Architecture (ISA), Micro-Channel Architecture (MSA), ExtendedISA (EISA), Intelligent Drive Electronics (IDE), VESA Local Bus (VLB),Peripheral Component Interconnect (PCI), Card Bus, Universal Serial Bus(USB), Advanced Graphics Port (AGP), Personal Computer Memory CardInternational Association bus (PCMCIA), Firewire (IEEE 1394), and SmallComputer Systems Interface (SCSI). The bus 120 can be a hardwired sharedphysical bus, for instance.

The computing system 100 illustrated in FIG. 1 is one example of such asystem; however, embodiments of the present disclosure are not limitedto the configuration shown in FIG. 1.

As illustrated in FIG. 1, the memory devices 130-1, . . . , 130-N cancomprise a number of dies and/or chips that can include a number ofmemory arrays 112-1, 112-2, . . . , 112-M providing storage volumes forthe memory system 104. The memory arrays 112-1, 112-2, . . . , 112-M caninclude peripheral circuitry thereon. In a number of embodiments, thememory arrays 112-1, 112-2, . . . , 112-M can be the minimum componentof memory system 104 capable of independently executing commands fromand/or sending status to the host 102 via host interface 106. The memoryarrays 112-1, 112-2, . . . , 112-M can include Flash memory arrayshaving a NAND architecture, for example. However, embodiments are notlimited to a particular type of memory array or array architecture andcould include memory arrays having RRAM, MRAM, STTRAM, and/or PCRAMmemory cells.

The embodiment illustrated in FIG. 1 can include additional circuitry,logic, and/or components not illustrated so as not to obscureembodiments of the present disclosure. For example, memory devices130-1, . . . , 130-N can include address circuitry to latch addresssignals provided over I/O connectors through I/O circuitry. Signals canbe received and decoded by a row decoder and a column decoder, to accessmemory system 102.

FIG. 2 illustrates examples of a method for command queuing in a memorysystem in accordance with a number of embodiments of the presentdisclosure. In FIG. 2, a queued command request 240-1, e.g., CMD 43, canbe sent from a host 202 to a memory system 204. The queued commandrequest 240-1 can indicate to the memory system 204 that the host 202would like to send a command to the memory system 204 for the memorysystem 204 to add to the command queue in the memory system 204. Thememory system 204 can send a command response 242-1 to the host, inresponse to receiving the queued command request. The command response242-1 can include a queue busy bit that is set to one (1), indicatingthat memory system 204 is not ready to receive commands in the commandqueue, e.g., the command queue is full. When the host 202 receivescommand response 242-1 with a queue busy bit set to one (1), the host202 does not send a command block descriptor back to the memory system204. In a number of embodiments, the host 202 can send a number ofqueued command requests to the memory system 204 until the memory system204 sends back a command response with a queue busy bit set to zero (0).For example, after a period of time, the host 202 can send anotherqueued command request 240-P to the memory system 204, which includesthe same information as queued command request 240-1. If the commandqueue in the memory system 204 is ready to receive commands to add tothe command queue, the memory system 204 can send command response 242-0with the queue busy bit set to zero (0) to the host 202, which indicatesthat the memory system 204 is ready to add commands to the commandqueue. The host 202 sends command descriptor block 244 to the memorysystem 204 and the memory system 204 places the command described in thecommand descriptor block 244 in the command queue. The commanddescriptor block 244 includes information regarding the command thatenables the host 202 and the memory system 204 to execute the commandwhen they are ready to execute commands.

In a number of embodiments, the host 202 can send a task managementfunction request command, e.g., CMD 45, to the memory system 204. Thetask management function request command can be used to check a statusregister, e.g. status register 127 in FIG. 1, to determine the status ofeach of the command in the command queue, e.g., command queue 126 inFIG. 1. The memory system 204 can return the status of each of thecommands in the command queue to the host 202. In a number ofembodiments, the task management function request command can also besent from the host 202 to the memory system 204 with an indication toabort the command queue, whereby each of the commands in the commandqueue are aborted by the memory system 204. Also, a stop command, e.g.,CMD 12 and/or a high priority interrupt (HPI) command can be sent fromthe host 202 to the memory system 204, which will cause the memorysystem 204 to abort the command queue.

In a number of embodiments, a number of commands can be added to thecommand queue when the host sends a number of queued command requests tothe memory system and then a number of command descriptor blocks to thememory system in response to receiving a number of command responsesindicating that the command queue is ready to receive commands. Thenumber of queued command requests can be received from the host on acommand line, so that queued command requests can be received by thememory system and responded to by the memory system while commands fromthe command queue are being executed in the memory system on a data bus.

FIG. 3 illustrates an example of a command block descriptor 344 inaccordance with a number of embodiments of the present disclosure. InFIG. 3, the command block descriptor 344 includes a number of fieldsthat provide information associated with a command so the command can beplaced in a command queue and executed according to the informationcontained in command block descriptor 344. A command block descriptorcan include 32 bytes, for example, among other numbers of bytes. In thisexample, command block descriptor 344 can include 32 bytes, where byte 0is associated with a command operation code 341, byte 1 is associatedwith command priority information 343, byte 2 is reserved, byte 3 isassociated with a command task tag 345, bytes 4 to 7 are associated withthe command argument 346, bytes 8 to 11 are associated with the commandstarting address 348, bytes 12 to 13 are reserved, bytes 14 to 15 areassociated with the command block count 349, and bytes 16 to 31 arereserved. By way of example, the command operation byte 341 can be setto a value of 01h, corresponding to a read command. The commandoperation byte 341 can be set to a value of 02h, corresponding to awrite command. The command priority information 343 can indicate anorder of priority for execution in the command queue. The commandpriority information 343 byte can be set to a value of 00h, whichcorresponds to a simple priority where the command is placed in thecommand queue without priority. The command priority information 343byte can be set to a value of 01h, which corresponds to an orderedpriority where the command is placed in the command queue so that thecommand is executed chronologically based on when the memory systemreceived the command. The command priority information 343 byte can beset to a value of 02h, which corresponds to a head-of-queue prioritywhere the command is the next executed command. The command task tag 345byte can correspond to a unique identifier that is used to distinguishthe command from other commands in the command queue. The command tasktag byte 345 can be set to values ranging from 00h to FFh. The commandargument 346, e.g., a reliable write or a forced programming request,command starting address 348, and the command block 349 count can be setto values according to e.MMC protocol.

In a number of embodiments, the command descriptor block can include anynumber of bytes, e.g. less than 32 bytes. For example, when someinformation, such as command priority, command tag, task attribute,command argument, and/or block count, among other information, isincluded in the queued command request, the command descriptor block canincludes less than 32 bytes.

FIGS. 4A-D illustrate examples of a method for executing commands in acommand queue in a memory system 404 in accordance with a number ofembodiments of the present disclosure. In FIG. 4A, once the host 402 hassent one or more commands to the command queue in the memory system 404,the host 402 can send a ready to transfer command 450, e.g., CMD 44, tothe memory system 404 when the host 402 is ready to transmit or receivedata. The memory system 404 can send data transfer request 452-0 to thehost 402 in response to receiving the ready to transfer command 450. Thedata transfer request 452-0 can correspond to a command in the commandqueue that is ready for execution next. In a number of embodiments, adata transfer request may provide a negative response and not request adata transfer if the memory system 404 is not ready to send or receivedata. In a number of embodiments, the data transfer request may bedelivered using the command/response signal and not using the data bus.The data transfer request 452-0 can include a direction bit thatindicates the direction of data transfer when execution the command. Forexample, a direction bit that is set to 1 indicates that the command isa write command where data is sent from the host to the memory system.The data transfer request 452-0 can include a command tag field toidentify which command from the command queue is being executed and canalso include a data offset field and a data size field to indicate whichportions of the data should be transferred. In FIG. 4A, data transferrequest 452-0, sent in response to receiving the ready to transfercommand, includes a direction bit set to 0, which indicates that thecommand is a read command where data is sent from the memory system tothe host. The direction bit that is set to 0 in the data transferrequest 452-0 allows the memory system 404 to maintain control of thebus and send the read data requested in the command from the memorysystem 404 to the host 402. The memory system 404 remains in a SendingData state when the direction bit of the data transfer request is set to0, therefore, in a number of embodiments, a data transfer request with adirection bit set to 0 does not cause a state change in the memorysystem 404. In a number of embodiments, the memory system can beconfigured so that the memory system 404 remains in a Sending Data statewhen the memory system 404 sends a data transfer request with adirection bit set to 0.

In FIG. 4B, once the host 402 has sent one or more commands to thecommand queue in the memory system 404, the host 402 can send a ready totransfer command 450, e.g., CMD 44, to the memory system 404 when thehost 402 is ready to transmit or receive data. The memory system 404 cansend a data transfer request 452-1, which includes a direction bit toindicate the direction of data transfer during execution of the command,to the host 402 in response to receiving the ready to transfer command450. In a number of embodiments, a data transfer request may provide anegative response and not request a data transfer if the memory system404 is not ready to send or receive data. In a number of embodiments,the data transfer request may be delivered using the command/responsesignal and not using the data bus. In FIG. 4B, data transfer request452-1, sent in response to receiving the ready to transfer command,includes a direction bit set to 1, which corresponds to a write command.The data transfer request 452-1 can include a command tag field toidentify which command from the command queue is being executed and canalso include a data offset field and a data size field to indicate whichportions of the data should be transferred. The direction bit that isset to 1 in the data transfer request 452-1 allows the host 402 to takecontrol of the bus and send the write data requested in the command fromthe host 402 to the memory system 404. The memory system 404 transitionsfrom a Sending Data state to a Receive Data state when the direction bitof the data transfer request 452-1 is set to the 1. In a number ofembodiments, the state machine of the memory system can be configured sothat the memory system 404 changes from a Sending Data state to aReceiving Data state when the memory system 404 sends a data transferrequest with a direction bit set to 1.

In FIG. 4C, once the host 402 has sent one or more commands to thecommand queue in the memory system 404, the host 402 can send a ready totransfer command 450, e.g., CMD 44, to the memory system 450 when thehost 402 is ready to transmit or receive data. The memory system 404 canrespond with a data transfer request 452-0, which includes a directionbit to indicate the direction of data transfer during execution of thecommand, to the host 402 in response to receiving the ready to transfercommand 450. In a number of embodiments, a data transfer request mayprovide a negative response and not request a data transfer if thememory system 404 is not ready to send or receive data. In a number ofembodiments, the data transfer request may be delivered using thecommand/response signal and not using the data bus. In FIG. 4C, datatransfer request 452-0 that was sent in response to receiving the readyto transfer command 450 includes a direction bit set to 0, whichcorresponds to a read command. The data transfer request 452-0 caninclude a command tag field to identify which command from the commandqueue is being executed and can also include a data offset field and adata size field to indicate which portions of the data should betransferred. In response to receiving the data transfer request 452-0with a direction bit set to 0, the host 402 sends a send data command458, e.g. CMD 47, to the memory system 404. The send data command 458requests memory system 404 to send data to the host 402, therefore thememory system 404 transitions from a Transfer state to a Sending Datastate and memory system 404 takes control of the bus and sends the readdata requested in the command from the memory system 404 to the host402. When all data has been transferred, the memory system 404 movesback from the Sending Data state to the Transfer state. In a number ofembodiments, the state machine of the memory system can be configured sothat the memory system 404 changes from a Sending Data state to aTransfer state after sending the transfer data request 452-0 and thenchanges from the Transfer state to a Sending Data state when the memorysystem 404 receives the send data command 458 from the host.

In FIG. 4D, once the host 402 has sent one or more commands to thecommand queue in the memory system 404, the host 402 can send a ready totransfer command 450, e.g., CMD 44, to the memory system 404 when thehost 402 is ready to transmit or receive data. The memory system 404 cansend data transfer request 452-1, which includes a direction bit toindicate the direction of data transfer during execution of the command,to the host 402 in response to receiving the ready to transfer command450. In a number of embodiments, a data transfer request may provide anegative response and not request a data transfer if the memory system404 is not ready to send or receive data. In a number of embodiments,the data transfer request may be delivered using the command/responsesignal and not using the data bus. In FIG. 4D, data transfer request452-1 that was sent in response to receiving the ready to transfercommand 450 includes a direction bit set to 1, which corresponds to awrite command. The data transfer request 452-1 can include a command tagfield to identify which command from the command queue is being executedand can also include a data offset field and a data size field toindicate which portions of the data should be transferred. In responseto receiving the data transfer request 452-1 with a direction bit set to1, the host 402 sends a receive data command 460, e.g. CMD 46, to thememory system 404. The receive data command 460 indicates to the memorysystem 404 that the memory system 404 will be receiving data from thehost 402, therefore the memory system 404 transitions from a Transferstate to a Receiving Data state and memory system 404 allows the host402 to take control of the bus and send the write data requested in thecommand from the host 402 to the memory system 404. When all data havebeen transferred, the memory system 404 moves back from the ReceivingData state to the Transfer state.

In a number of embodiments, the state machine of the memory system canbe configured so that the memory system 404 changes from a Sending Datastate to a Transfer state after sending the transfer data request andthen changes from the Transfer state to a Receiving Data state when thememory system 404 receives the receive data command 460 from the host402.

In a number of embodiments, when an error occurs during the execution ofa command, the command fails. The memory system can respond toadditional queued command requests from the host with a command responsewith error bits indicating that there was an error during execution of acommand. The host can also query the memory system with a taskmanagement function request command to receive an update on the statusof the commands in the command queue.

FIG. 5 illustrates an example of a data transfer request header 552included in a data transfer request in accordance with a number ofembodiments of the present disclosure. In FIG. 5, the data transferrequest header 552 includes a number of fields that provide informationassociated with a command so the command can be identified by the hostand executed by the host and memory device. A data transfer requestheader can include 32 bits, for example, among other numbers of bits.Data transfer request header 552 includes 32 bytes, where bytes 0 to 1are reserved, byte 2 is associated with a transfer direction 551, byte 3is associated with a command task tag 545, bytes 4 to 11 are reserved,bytes 12 to 13 are associated with the data buffer offset 553, bytes 14to 15 are associated with the command transfer length 555, bytes 16 to31 are reserved. The transfer direction 551 byte can be set to a valueof ooh, corresponding to a read command. The transfer direction 551 bytecan be set to a value of 01h, corresponding to a write command. Thecommand task tag 545 byte can correspond to a unique identifier that isused to distinguish and identify the command from other commands in thecommand queue that will be executed. The command task tag 545 byte canbe set to values ranging from 00h to FFh. The data buffer offset 553 canbe an offset of a data transfer within the complete data transfer of atask. The data transfer request 552 may be composed of any number ofbytes. For example, the data transfer request may be composed of lessthan 32 bytes when the data transfer request is delivered using thecommand/response signal, even if including the same fields previouslydescribed.

FIG. 6 illustrates an example of a method for command queuing andexecution in a memory system in accordance with a number of embodimentsof the present disclosure. The method illustrated in FIG. 6 includes anumber of commands that are executed concurrently, where commands andcommand responses are sent between a host and a memory system on acommand line, while data associated with the commands is beingtransferred between the memory system and the host on a data bus.Therefore, in a number of embodiments, the data bus can be controlled bythe host or the memory system based on the commands that are sent on thecommand line and the data bus can be in use transferring data betweenthe host and the memory device while commands are being sent on thecommand line. For example, a command can be added to the command queuevia commands that are sent between the host and memory system while dataassociated with commands in the command queue is sent between the hostand the memory system on the data bus.

In FIG. 6, a first queued command request 640-1, e.g., CMD 43,associated with a first command 647-1 is sent from the host 602 to thememory system 604. The first command 647-1 is a 4 KB read command. Inresponse, the memory system 604 can send a command response (not shown)and the host 602 can send a command block descriptor (not shown) for thefirst command so the first command 647-1 can be added to the commandqueue.

A second queued command request 640-2, e.g., CMD 43, associated with asecond command 647-2 is sent from the host 602 to the memory system 604.The second command 647-2 is 16 KB write command. In response, the memorysystem 604 can send a command response (not shown) and the host 602 cansent a command block descriptor (not shown) for the second command sothe second command 647-2 can be added to the command queue. The commandqueue now has two commands, the first command 647-1 and the secondcommand 647-2, ready for execution.

A ready to transfer command 650-1, e.g. CMD 44, is sent from the host602 to the memory system 604 on the command line 605. In FIG. 6, thememory system 604 is not ready to execute a command and sends a commandresponse indicating such to the host 602. The host 602, after a timeperiod, then sends the ready to transfer command 650-1, e.g., CMD 44, tothe memory system 604 again. The memory system 604 responds to the readyto transfer command 650-1 with data transfer request 652-1 identifyingthe command, 4 KB read command 647-1, and the direction of datatransfer. The host 602, in response to receiving the data transferrequest 652-1, sends a send data command 658-1, e.g., CMD 47, causingthe memory system 604 to take control of the data bus 606 and send 4 KBof data 657-1 associated with the first command 647-1.

While the 4 KB of data associated with the first command 647-1 is beingsent from the memory system 604 to the host 602 on the data bus 606, aready to transfer command 650-2, e.g. CMD 44, and a third queued commandrequest 640-3, e.g., CMD 43, associated with a third command 647-3 issent from the host 602 to the memory system 604 on the command line 605.The third command 647-3 is added to the command queue when the memorysystem 604 sends a command response (not shown) to the third queuedcommand request 640-3 and the host 602 can send a command blockdescriptor (not shown) for the third command so the third command 647-3can be added to the command queue. The memory system 604 responds to theready to transfer command 650-2 with data transfer request 652-2identifying the second command 647-2, a 16 KB write command, thedirection of data transfer, and the portion of the data to betransferred, e.g. data offset and data size. The host 602, in responseto receiving data transfer request 652-2, sends a receive data command660-2, e.g., CMD 46, causing the host 602 to take control of the databus 606 and send 8 KB of data 657-2 associated with the second command647-2 to the memory system 604.

While the 8 KB of data associated with the second command 647-2 is beingsent from the host 602 to the memory system 604 on the data bus 606, aready to transfer command 650-3, e.g. CMD 44, is sent from the host 602to the memory system 604 on the command line 605. The memory system 604responds to the ready to transfer command 650-3 by sending data transferrequest 652-3 on the command line 605 identifying the third command647-3, a 8 KB read command, and the direction of data transfer. Thepriority indicated in the third command 647-3 was higher priority thancommand 647-2, therefore the command 647-3 is executed next and theexecution of the second command 647-2 is paused, e.g. with only 8 KB ofthe 16 KB associated with the second command 647-2 having been sent fromthe host 602 to the memory system 604, while the third command isexecuted. The host 602, in response to receiving data transfer request652-3, sends a send data command 658-3, e.g., CMD 47, causing the memorysystem 604 to take control of the data bus 606 and send 8 KB of data657-3 associated with the third command 647-3.

A fourth queued command request 640-4, e.g., CMD 43, associated with afourth command 647-4 is sent from the host 602 to the memory system 604.The fourth command 647-4 is 8 KB read command. In response, the memorysystem 604 can send a command response (not shown) and the host 602 cansend a command block descriptor (not shown) for the fourth command sothe fourth command 647-4 can be added to the command queue. The commandqueue now has three commands, the second command 647-2, which has beenpartially executed, and the third command 647-3, which is beingexecuted, and the fourth command 647-4, which is ready for execution.

While the 8 KB of data associated with the third command 647-3 is beingsent from the memory system 604 to the host 602 on the data bus 606,ready to transfer command 650-2, e.g. CMD 44, is again sent from thehost 602 to the memory system 604 on the command line 605, so thatexecution of the second command 647-2 may resume. The memory system 604responds to the ready to transfer command 650-2 with data transferrequest 652-2 identifying the second command 647-2, a 16 KB writecommand, the direction of data transfer, and the portion of the data tobe transferred, e.g., data offset and data size. The host 602, inresponse to receiving data transfer request 652-2, sends a receive datacommand 660-2, e.g., CMD 46, causing the host 602 to take control of thedata bus 606 and send 8 KB of data 657-2 associated with the secondcommand 647-2 to the memory system 604 to complete execution of thesecond command 647-2.

While the 8 KB of data associated with the second command 647-2 is beingsent from the host 602 to the memory system 604 on the data bus 606, aready to transfer command 650-4, e.g. CMD 44, is sent from the host 602to the memory system 604 on the command line 605. The memory system 604responds to the ready to transfer command 650-4 with data transferrequest 652-4 identifying the fourth command 647-4, a 8 KB read command,and the direction of data transfer. The host 602, in response toreceiving data transfer request 652-4, sends a send data command 658-4,e.g., CMD 47, causing the memory system 604 to take control of the databus 606 and send 8 KB of data 657-4 associated with the fourth command647-4.

The host 602 sends ready to transfer commands 650-5 and 650-6 to thememory system 604, but the command queue is empty, so the memory system604 sends a command response (not shown) to the host 602 indicating thatthe command queue is empty and/or the memory system 604 does not send adata transfer request in response to command 650-5 and 650-6.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of a number of embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of ordinary skill in the artupon reviewing the above description. The scope of a number ofembodiments of the present disclosure includes other applications inwhich the above structures and methods are used. Therefore, the scope ofa number of embodiments of the present disclosure should be determinedwith reference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

In the foregoing Detailed Description, some features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thus,the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment.

1-20. (canceled)
 21. A method for command queuing, comprising: receivinga command at the memory system from a host, wherein the command includesa command descriptor block; and placing, in response to receiving thecommand descriptor block, the command described by the commanddescriptor block in the command queue of the memory system.
 22. Themethod of claim 21, wherein the command descriptor block includespriority information for the command.
 23. The method of claim 22,wherein the priority information includes a parameter that indicates thecommand is placed in the command queue with highest priority forexecution.
 24. The method of claim 22, wherein the priority informationincludes a parameter that indicates the command is placed in the commandqueue with chronological priority for execution.
 25. The method of claim22, wherein the priority information includes a parameter that indicatesthe command is placed in the command queue without priority forexecution.
 26. The method of claim 21, wherein the command descriptorblock for the command includes a command operation code, priorityinformation, a task tag, a command argument, a starting address, and ablock count.
 27. The method of claim 21, wherein the method includesreceiving the command at the memory system when the memory system is ina Transfer state.
 28. The method of claim 21, wherein the methodincludes changing the memory system from a Transfer state to a Receivingstate in response to sending a command response.
 29. The method of claim21, wherein the method includes command queuing using an embeddedMultiMediaCard (e.MMC) protocol.
 30. The method of claim 21, wherein themethod includes executing the command by receiving a ready to transfercommands at the memory system from the host.
 31. An apparatus,comprising: a controller; and a memory device coupled to the controller,wherein the apparatus is configured to: place a command in a commandqueue in response to receiving the command that includes a commanddescriptor block; and execute the command in response to receiving aready to transfer command.
 32. The apparatus of claim 31, whereinapparatus is configured to execute the command by receiving a receivedata command at the controller from the host, transitioning from aTransfer state to a Receiving Data state, and receiving data at theapparatus from the host.
 33. The apparatus of claim 31, whereinapparatus is configured to execute the command by receiving a send datacommand at the controller from the host, transitioning from a Transferstate to a Sending Data state, and sending data from the memory deviceto the host.
 34. The apparatus of claim 31, wherein the apparatus isconfigured to receive a task management function request command fromthe host and send a status of each of a number of commands in thecommand queue to the host.
 35. The apparatus of claim 31, wherein theapparatus is configured to receive a task management function requestcommand from the host and abort each of a number of commands in thecommand queue.
 36. A method for command queuing, comprising: receiving afirst command at a memory system from a host, wherein the first commandincludes a first command descriptor block; placing, in response toreceiving the first command descriptor block, the first command in acommand queue of the memory system; executing the first command inresponse to receiving a ready to transfer command; receiving a secondcommand at the memory system from the host, wherein the second commandincludes a second command descriptor block; and placing, in response toreceiving the second command descriptor block, the second command in thecommand queue of the memory system while executing the first command.37. The method of claim 36, further including interrupting the executionof the first command and executing the second command in response to thesecond command being placed in the command queue with a parameter thatindicates the second command is placed in the command queue with highestpriority for execution.
 38. The method of claim 36, wherein the methodincludes executing the second command by receiving a ready to transfercommand at the memory system from the host and sending a data transferrequest from the memory system to the host in response to receiving theready to transfer command, wherein the data transfer request includes adata packet with information allowing for command execution on the hostand memory system.
 39. The method of claim 36, wherein the methodincludes receiving the second command at the memory system from the hoston a command line while the first number of command is being executedvia data transfers on a data bus.
 40. The method of claim 36, the methodincludes resuming execution of the first command after execution of thesecond command has commenced.